The present application is based on and claims priority from Japanese Patent Application Hei 11-96513 filed on Apr. 2, 1999, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method of manufacturing a stator of a rotary electric machine.
2. Description of the Related Art
WO92/06527 (PCT/DE91/00738) discloses a method of manufacturing a stator, in which both U-shaped and I-shaped conductor segments are inserted into slots of a stator core from one or a first end of the stator core so that pairs of straight portions of the U-shaped conductor segments extend from the other or the second end of the stator core to be welded to one another, thereby forming a stator winding. One straight portion of each pair is inserted to a slot that is electric angle xcfx80 radian spaced apart from the slots to which the other straight portion is inserted. The I-shaped conductor segments are inserted into slots separately to connect the straight portion of the U-shaped conductor segments at the second end of the stator and to extend from the first end of the stator.
However, it is difficult to retain the I-shaped conductor segments in the slots without additional retaining members because of the shape thereof.
A main object of the invention is to provide an improved method of manufacturing a stator of a rotary electric machine that solve the above-stated problem.
Another object of the invention is to provide a method of manufacturing such a stator without using the I-shaped conductor segments, in which connection work can be done easily.
According to a main feature of the invention, a method of manufacturing a stator of a rotary electric machine is comprised of the following steps: providing a plurality of U-shaped basic conductor segments and a plurality of U-shaped connection conductor segments; forming the U-turn portion and pair of straight portions of the basic and connection conductor segments into first crossover portions; inserting the pair of straight portions of the basic and connection conductor segments into prescribed two slots from one end of a stator core; bending each of the pair of straight portions of the basic and connection conductor segments extending from the other end in directions opposite to each other so that the edges of the straight portions extending from the prescribed two slots can adjoin each other; connecting the adjoining edges to form second crossover portions; and removing the U-turn portion of the connection conductor segments to respectively form terminals of the coils.
Thus, it is not necessary to insert I-shaped conductor segments in the slots. This can saves additional retaining members. In addition, the straight portions of the connection segments are extended to be connected on only one end of the stator core, so that connection work can be done easily.
According to an additional feature of the invention, each of the slots has outermost first slot layer, outer-middle second slot layer, inner-middle third slot layer, and innermost fourth slot layer. The basic conductor segments are comprised of comprise large segments having straight portions to be disposed in the first and fourth slot layers and small segments having the straight portions to be disposed in the second and third slot layers. The connection conductor segments are comprised of first connection segments having the U-turn portion to be removed and the straight portions to be disposed in the first and third slot layers and second connection segments having the straight portions to be disposed in the second and fourth slot layers.
This feature prevents each conductor segments from overlapping each other and reduces the number of specific segments.
According to another feature of the invention, the step of forming U-turn portion and the straight portions is comprised of a step of holding the straight portions to be disposed in the first and second slot layers by an outer ring and the straight portion to be disposed in the third and fourth slot layers by an inner ring coaxially rotatable within the outer ring and a step of rotating the outer and inner rings relative to each other in a prescribed angle.
This feature makes the forming step easy and reliable.
According to additional feature of the invention, the step of bending is comprised of a step of holding the edges of the straight portions extending from the four slot layers by separate four rings and a step of rotating the four rings relative to each other in a prescribed angle.
This feature also makes the bending step easy and reliable.